#include <stdio.h>


int main()
{
  FILE *fp=fopen("log.txt","a");
  if(NULL == fp)
  {
    perror("fopen");
    return 1;
  }

  fprintf(fp,"hello world!%d,%s,%lf\n",10,"abcdefg",3.14);

  fclose(fp);

  return 0;
}
